Why I Can't Teach You the Legion Handshake

The Legion of Super-Heroes is an exclusive club, complete with a constitution, hazing, and a club house. And its own secret handshake, of course. Here it is from Adventure Comics #290:

At which point it had to be immediately changed, so don't try to fake your way into a Legion meeting. Why? Because Superboy is a supreme DUMBASS, that's why.

This is him essentially demonstrating the handshake to a fake Sun Boy who (literally) showed his hand by not using it at the appropriate time. Problem is, you can't go showing this stuff to an infiltrator if it's what you use to defeat infiltrators.